Will my DSII work

I just got a recycled 78 DSII. While cleaning and recurving i noticed that the shaft moves slightly up and down. Is that normal or did I buy a dud? Holding the base where the vacuum is attached i can move the post that the reluctor is on about 1/32 - 1/16 up and down. Same with the shaft coming out the bottom.

Normal end play in the distributor shaft to housing.
The critical measurment is from the bottom of the housing flange to the bottom of the gear. 2.510-2.515" with the end play of the gear against the housing.
See classicinlines.com website & it is explaned very well. Bill

Thanks, I measured from the very bottom of the gear to the housing with a crude framing tape and came up with 2.5" and a hair. Got the Recurve spring in, put everything back together. Now i'm just waiting on mikes Dyna module. I assume it pretty easy to attach a tach if I wanted. Has anyone found a good after market tach that will fit in the clock opening on a 67?

IIRC the allowable axial play is .020